Dressing with differentially sized perforations

ABSTRACT

A dressing for treating a tissue site may include a base layer, a sealing member, a first and a second wicking layer, and an absorbent layer. The base layer may have a periphery surrounding a central portion and a plurality of apertures disposed through the periphery and the central portion. The apertures in the periphery may be larger than the apertures in the central portion. The sealing member and the base layer may define an enclosure. The first and the second wicking layer may each be disposed in the enclosure with the absorbent layer positioned between the first and the second wicking layer. Other dressings, systems, and methods are disclosed.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No. 16/007,060, filed Jun. 13, 2018, which is a continuation of U.S. patent application Ser. No. 14/490,918, filed Sep. 19, 2014, now U.S. Pat. No. 10,016,544, which claims the benefit, under 35 USC § 119(e), of the filing of U.S. Provisional Patent Application Ser. No. 61/897,640, entitled “DRESSING WITH DIFFERENTIALLY SIZED PERFORATIONS,” filed Oct. 30, 2013, which are incorporated herein by reference for all purposes.

FIELD

This disclosure relates generally to medical treatment systems and, more particularly, but not by way of limitation, to absorbent dressings, systems, and methods for treating a tissue site with reduced pressure.

BACKGROUND

Depending on the medical circumstances, reduced pressure may be used for, among other things, reduced-pressure therapy to encourage granulation at a tissue site, draining fluids at a tissue site, closing a wound, reducing edema, promoting perfusion, and fluid management. Common dressings, systems, and methods may be susceptible to leaks and blockage that can cause a reduction in the efficiency of the therapy or a complete loss of therapy. Such a situation can occur, for example, if the amount of fluid in the dressing or system exceeds the fluid capacity of the dressing or system. Further, the formation of condensate in the dressing or system may create similar concerns. Leaks, blockages, and condensate in the dressing or system may also be perceptible by a user and may lack visual appeal. Prevention of leaks and blockages may be particularly important when only a limited power supply to the reduced pressure source and other components is available. Thus, improvements to dressings, systems, and methods that enhance the management of fluid extracted from a tissue site for increasing reliability, efficiency, visual appeal, and the useable life of the dressing and system are desirable.

SUMMARY

Shortcomings with certain aspects of tissue treatment dressings, systems, and methods are addressed as shown and described in a variety of illustrative, non-limiting embodiments herein.

In some embodiments, a system for treating a tissue site may include a tissue interface, a dressing, and a reduced-pressure source. The tissue interface may be adapted to be positioned proximate to the tissue site. The dressing may include a base layer, an adhesive, a sealing member, a first wicking layer, a second wicking layer, an absorbent layer, and a conduit interface. The base layer may have a periphery surrounding a central portion and a plurality of apertures disposed through the periphery and the central portion. The apertures in the periphery may be larger than the apertures in the central portion. Further, the base layer may be adapted to cover the tissue interface and tissue surrounding the tissue site. The adhesive may be in fluid communication with the apertures at least in the periphery of the base layer. The sealing member may have a periphery and a central portion. The periphery of the sealing member may be positioned proximate to the periphery of the base layer such that the central portion of the sealing member and the central portion of the base layer define an enclosure. The first wicking layer and the second wicking layer may each be disposed in the enclosure. The absorbent layer may be disposed between the first wicking layer and the second wicking layer. The conduit interface may be positioned proximate to the sealing member and in fluid communication with the enclosure. The reduced-pressure source may be adapted to be coupled in fluid communication with the conduit interface to provide reduced pressure to the dressing.

In other embodiments, a dressing for treating a tissue site may include a base layer, an adhesive, a sealing member, a first wicking layer, a second wicking layer, an absorbent layer, and a conduit interface. The base layer may have a periphery surrounding a central portion and a plurality of apertures disposed through the periphery and the central portion. The apertures in the periphery may be larger than the apertures in the central portion. The base layer may be adapted to cover the tissue site. The adhesive may be in fluid communication with the apertures in the base layer. The sealing member may have a periphery and a central portion. The periphery of the sealing member may be positioned proximate to the periphery of the base layer such that the central portion of the sealing member and the central portion of the base layer define an enclosure. The first wicking layer and the second wicking layer may each be disposed in the enclosure. The absorbent layer may be positioned in fluid communication between the first wicking layer and the second wicking layer. A peripheral portion of the first wicking layer may be coupled to a peripheral portion of the second wicking layer providing a wicking layer enclosure surrounding the absorbent layer between the first and the second wicking layer. The conduit interface may be positioned proximate to the sealing member and in fluid communication with the enclosure.

In other embodiments, a system for treating a tissue site may include a tissue interface, a dressing, and a reduced-pressure source. The tissue interface may be adapted to be positioned proximate to the tissue site and to distribute reduced pressure to the tissue site. The dressing may be adapted to provide reduced pressure to the tissue interface and to store fluid extracted from the tissue site through the tissue interface. The dressing may include a base layer, an adhesive, a sealing member, a first wicking layer, a second wicking layer, an absorbent layer, and a conduit interface. The base layer may have a periphery surrounding a central portion and a plurality of apertures disposed through the periphery and the central portion. The apertures in the periphery may be larger than the apertures in the central portion. The base layer may additionally include a border substantially surrounding the central portion and positioned between the central portion and the periphery. The border may be free of apertures. The central portion of the base layer may be adapted to be positioned proximate to the tissue interface and the periphery of the base layer may be adapted to be positioned proximate to tissue surrounding the tissue site. Further, the periphery of the base layer may be adapted to surround the tissue interface, and the apertures in the base layer may be adapted to be in fluid communication with the tissue interface and the tissue surrounding the tissue site. The adhesive may be in fluid communication with the apertures in the base layer. Further, the adhesive may be adapted to be in fluid communication with the tissue surrounding the tissue site through the apertures in the base layer. The sealing member may have a periphery and a central portion. The periphery of the sealing member may be positioned proximate to the periphery of the base layer such that the central portion of the sealing member and the central portion of the base layer define an enclosure. The first wicking layer and the second wicking layer may each be disposed in the enclosure. The absorbent layer may be positioned in fluid communication between the first wicking layer and the second wicking layer. The conduit interface may positioned proximate to the sealing member and in fluid communication with the enclosure. The reduced-pressure source may be adapted to be coupled in fluid communication with the conduit interface to provide reduced pressure to the dressing.

Other aspects, features, and advantages of the illustrative embodiments will become apparent with reference to the drawings and detailed description that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away view of an illustrative embodiment of a system for treating a tissue site depicting an illustrative embodiment of a dressing deployed at a tissue site;

FIG. 2 is a cut-away view of the dressing of FIG. 1 ;

FIG. 3 is detail view taken at reference FIG. 3 , depicted in FIG. 1 , illustrating the dressing of FIG. 1 positioned proximate to tissue surrounding the tissue site;

FIG. 4A is an exploded view of the dressing of FIG. 1 , depicted without a conduit interface and with an illustrative embodiment of a release liner for protecting the dressing prior to application at a tissue site;

FIG. 4B is a plan view of an illustrative embodiment of a base layer depicted in the dressing of FIG. 4A;

FIG. 5 is a cut-away view of an illustrative embodiment of a fluid management assembly according to the dressing and system of FIG. 1 ;

FIG. 6 is a cut-away view of another illustrative embodiment of a fluid management assembly according to the dressing and system of FIG. 1 ;

FIG. 7 is a cut-away view of an illustrative embodiment of a conduit interface depicted in the dressing of FIG. 1 ;

FIG. 8 is a cut-away view of another illustrative embodiment of a fluid management assembly suitable for use with the dressing and system of FIG. 1 ;

FIG. 9A is a cross-section of an illustrative embodiment of a multi-lumen conduit suitable for use with the dressing and system of FIG. 1 ;

FIG. 9B is a cross-section of another illustrative embodiment of a multi-lumen conduit suitable for use with the dressing and system of FIG. 1 ;

FIG. 9C is a cross-section of another illustrative embodiment of a multi-lumen conduit suitable for use with the dressing and system of FIG. 1 ;

FIG. 9D is a cross-section of another illustrative embodiment of a multi-lumen conduit suitable for use with the dressing and system of FIG. 1 ; and

FIG. 9E is a cross-section of another illustrative embodiment of a multi-lumen conduit suitable for use with the dressing and system of FIG. 1 .

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following detailed description of non-limiting, illustrative embodiments, reference is made to the accompanying drawings that form a part hereof. Other embodiments may be utilized, and logical, structural, mechanical, electrical, and chemical changes may be made without departing from the scope of the appended claims. To avoid detail not necessary to enable those skilled in the art to practice the embodiments described herein, the description may omit certain information known to those skilled in the art. The following detailed description is non-limiting, and the scope of the illustrative embodiments are defined by the appended claims. As used herein, unless otherwise indicated, “or” does not require mutual exclusivity.

Referring to the drawings, FIG. 1 depicts an embodiment of a system 102 for treating a tissue site 104 of a patient. The tissue site 104 may extend through or otherwise involve an epidermis 106, a dermis 108, and a subcutaneous tissue 110. The tissue site 104 may be a sub-surface tissue site as depicted in FIG. 1 that extends below the surface of the epidermis 106. Further, the tissue site 104 may be a surface tissue site (not shown) that predominantly resides on the surface of the epidermis 106, such as, for example, an incision. The system 102 may provide therapy to, for example, the epidermis 106, the dermis 108, and the subcutaneous tissue 110, regardless of the positioning of the system 102 or the type of tissue site. The system 102 may also be utilized without limitation at other tissue sites.

Further, the tissue site 104 may be the bodily tissue of any human, animal, or other organism, including bone tissue, adipose tissue, muscle tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, ligaments, or any other tissue. Treatment of tissue site 104 may include removal of fluids, e.g., exudate or ascites.

Continuing with FIG. 1 , the system 102 may include an optional tissue interface, such as an interface manifold 120. Further, the system 102 may include a dressing 124, and a reduced-pressure source 128. The reduced-pressure source 128 may be a component of an optional therapy unit 130 as shown in FIG. 1 . In some embodiments, the reduced-pressure source 128 and the therapy unit 130 may be separate components. As indicated above, the interface manifold 120 is an optional component that may be omitted for different types of tissue sites or different types of therapy using reduced pressure, such as, for example, epithelialization. If equipped, the interface manifold 120 may be adapted to be positioned proximate to or adjacent to the tissue site 104, such as, for example, by cutting or otherwise shaping the interface manifold 120 in any suitable manner to fit the tissue site 104. As described below, the interface manifold 120 may be adapted to be positioned in fluid communication with the tissue site 104 to distribute reduced pressure to the tissue site 104. In some embodiments, the interface manifold 120 may be positioned in direct contact with the tissue site 104. The tissue interface or the interface manifold 120 may be formed from any manifold material or flexible bolster material that provides a vacuum space, or treatment space, such as, for example, a porous and permeable foam or foam-like material, a member formed with pathways, a graft, or a gauze. As a more specific, non-limiting example, the interface manifold 120 may be a reticulated, open-cell polyurethane or polyether foam that allows good permeability of fluids while under a reduced pressure. One such foam material is the VAC® GranuFoam® material available from Kinetic Concepts, Inc. (KCI) of San Antonio, Tex. Any material or combination of materials may be used as a manifold material for the interface manifold 120 provided that the manifold material is operable to distribute or collect fluid. For example, herein the term manifold may refer to a substance or structure that is provided to assist in delivering fluids to or removing fluids from a tissue site through a plurality of pores, pathways, or flow channels. The plurality of pores, pathways, or flow channels may be interconnected to improve distribution of fluids provided to and removed from an area around the manifold. Examples of manifolds may include, without limitation, devices that have structural elements arranged to form flow channels, cellular foam, such as open-cell foam, porous tissue collections, and liquids, gels, and foams that include or cure to include flow channels.

A material with a higher or lower density than GranuFoam® material may be desirable for the interface manifold 120 depending on the application. Among the many possible materials, the following may be used: GranuFoam® material, Foamex® technical foam (www.foamex.com), a molded bed of nails structures, a patterned grid material such as those manufactured by Sercol Industrial Fabrics, 3D textiles such as those manufactured by Baltex of Derby, U.K., a gauze, a flexible channel-containing member, a graft, etc. In some instances, ionic silver may be added to the interface manifold 120 by, for example, a micro bonding process. Other substances, such as anti-microbial agents, may be added to the interface manifold 120 as well.

In some embodiments, the interface manifold 120 may comprise a porous, hydrophobic material. The hydrophobic characteristics of the interface manifold 120 may prevent the interface manifold 120 from directly absorbing fluid, such as exudate, from the tissue site 104, but allow the fluid to pass through.

Continuing with FIG. 1 , the dressing 124 may be adapted to provide reduced pressure from the reduced-pressure source 128 to the interface manifold 120, and to store fluid extracted from the tissue site 104 through the interface manifold 120. The dressing 124 may include a base layer 132, an adhesive 136, a sealing member 140, a fluid management assembly 144, and a conduit interface 148. Components of the dressing 124 may be added or removed to suit a particular application.

Referring to FIGS. 1-4B, the base layer 132 may have a periphery 152 surrounding a central portion 156, and a plurality of apertures 160 disposed through the periphery 152 and the central portion 156. The base layer 132 may also have corners 158 and edges 159. The corners 158 and the edges 159 may be part of the periphery 152. One of the edges 159 may meet another of the edges 159 to define one of the corners 158. Further, the base layer 132 may have a border 161 substantially surrounding the central portion 156 and positioned between the central portion 156 and the periphery 152. The border 161 may be free of the apertures 160. The base layer 132 may cover the interface manifold 120 and tissue surrounding the tissue site 104 such that the central portion 156 of the base layer 132 is positioned adjacent to or proximate to the interface manifold 120, and the periphery 152 of the base layer 132 is positioned adjacent to or proximate to tissue surrounding the tissue site 104. In this manner, the periphery 152 of the base layer 132 may surround the interface manifold 120. Further, the apertures 160 in the base layer 132 may be in fluid communication with the interface manifold 120 and tissue surrounding the tissue site 104.

The apertures 160 in the base layer 132 may have any shape, such as, for example, circles, squares, stars, ovals, polygons, slits, complex curves, rectilinear shapes, triangles, or other shapes. The apertures 160 may be formed by cutting, by application of local RF energy, or other suitable techniques for forming an opening. As shown in FIGS. 4A-4B, each of the apertures 160 of the plurality of apertures 160 may be substantially circular in shape, having a diameter and an area. The area of each of the apertures 160 may refer to an open space or open area defining each of the apertures 160. The diameter of each of the apertures 160 may define the area of each of the apertures 160. For example, the area of one of the apertures 160 may be defined by multiplying the square of half the diameter of the aperture 160 by the value 3.14. Thus, the following equation may define the area of one of the apertures 160: Area=3.14*(diameter/2){circumflex over ( )}2. The area of the apertures 160 described in the illustrative embodiments herein may be substantially similar to the area in other embodiments (not shown) for the apertures 160 that may have non-circular shapes. The diameter of each of the apertures 160 may be substantially the same, or each of the diameters may vary depending, for example, on the position of the aperture 160 in the base layer 132. For example, the diameter of the apertures 160 in the periphery 152 of the base layer 132 may be larger than the diameter of the apertures 160 in the central portion 156 of the base layer 132. Further, the diameter of each of the apertures 160 may be between about 1 millimeter to about 50 millimeters. In some embodiments, the diameter of each of the apertures 160 may be between about 1 millimeter to about 20 millimeters. The apertures 160 may have a uniform pattern or may be randomly distributed on the base layer 132. The size and configuration of the apertures 160 may be designed to control the adherence of the dressing 124 to the epidermis 106 as described below.

Referring to FIGS. 4A-4B, in some embodiments, the apertures 160 positioned in the periphery 152 may be apertures 160 a, the apertures 160 positioned at the corners 158 of the periphery 152 may be apertures 160 b, and the apertures 160 positioned in the central portion 156 may be apertures 160 c. The apertures 160 a may have a diameter between about 9.8 millimeters to about 10.2 millimeters. The apertures 160 b may have a diameter between about 7.75 millimeters to about 8.75 millimeters. The apertures 160 c may have a diameter between about 1.8 millimeters to about 2.2 millimeters. The diameter of each of the apertures 160 a may be separated from one another by a distance A between about 2.8 millimeters to about 3.2 millimeters. Further, the diameter of at least one of the apertures 160 a may be separated from the diameter of at least one of the apertures 160 b by the distance A. The diameter of each of the apertures 160 b may also be separated from one another by the distance A. A center of one of the apertures 160 c may be separated from a center of another of the apertures 160 c in a first direction by a distance B between about 2.8 millimeters to about 3.2 millimeters. In a second direction transverse to the first direction, the center of one of the apertures 160 c may be separated from the center of another of the apertures 160 c by a distance C between about 2.8 millimeters to about 3.2 millimeters. As shown in FIGS. 4A-4B, the distance B and the distance C may be increased for the apertures 160 c in the central portion 156 being positioned proximate to or at the border 161 compared to the apertures 160 c positioned away from the border 161.

As shown in FIGS. 4A-4B, the central portion 156 of the base layer 132 may be substantially square with each side of the central portion 156 having a length D between about 100 millimeters to about 108 millimeters. In some embodiments, the length D may be between about 106 millimeters to about 108 millimeters. The border 161 of the base layer 132 may have a width E between about 4 millimeters to about 11 millimeters and may substantially surround the central portion 156 and the apertures 160 c in the central portion 156. In some embodiments, the width E may be between about 9 millimeters to about 10 millimeters. The periphery 152 of the base layer 132 may have a width F between about 25 millimeters to about 35 millimeters and may substantially surround the border 161 and the central portion 156. In some embodiments, the width F may be between about 26 millimeters to about 28 millimeters. Further, the periphery 152 may have a substantially square exterior with each side of the exterior having a length G between about 154 millimeters to about 200 millimeters. In some embodiments, the length G may be between about 176 millimeters to about 184 millimeters. Although FIGS. 4A-4B depict the central portion 156, the border 161, and the periphery 152 of the base layer 132 as having a substantially square shape, these and other components of the base layer 132 may have any shape to suit a particular application. Further, the dimensions of the base layer 132 as described herein may be increased or decreased, for example, substantially in proportion to one another to suit a particular application. The use of the dimensions in the proportions described above may enhance the cosmetic appearance of a tissue site. For example, these proportions may provide a surface area for the base layer 132, regardless of shape, that is sufficiently smooth to enhance the movement and proliferation of epithelial cells at the tissue site 104, and reduce the likelihood of granulation tissue in-growth into the dressing 124.

The base layer 132 may be a soft, pliable material suitable for providing a fluid seal with the tissue site 104 as described herein. For example, the base layer 132 may comprise a silicone gel, a soft silicone, hydrocolloid, hydrogel, polyurethane gel, polyolefin gel, hydrogenated styrenic copolymer gels, a foamed gel, a soft closed cell foam such as polyurethanes and polyolefins coated with an adhesive described below, polyurethane, polyolefin, or hydrogenated styrenic copolymers. The base layer 132 may have a thickness between about 500 microns (μm) and about 1000 microns (μm). In some embodiments, the base layer 132 has a stiffness between about 5 Shore 00 and about 80 Shore 00. The base layer 132 may be comprised of hydrophobic or hydrophilic materials.

In some embodiments (not shown), the base layer 132 may be a hydrophobic-coated material. For example, the base layer 132 may be formed by coating a spaced material, such as, for example, woven, nonwoven, molded, or extruded mesh with a hydrophobic material. The hydrophobic material for the coating may be a soft silicone, for example. In this manner, the adhesive 136 may extend through openings in the spaced material analogous to the apertures 160 described below.

The adhesive 136 may be in fluid communication with the apertures 160 in at least the periphery 152 of the base layer 132. In this manner, the adhesive 136 may be in fluid communication with the tissue surrounding the tissue site 104 through the apertures 160 in the base layer 132. As described below and shown in FIG. 3 , the adhesive 136 may extend or be pressed through the plurality of apertures 160 to contact the epidermis 106 for securing the dressing 124 to, for example, the tissue surrounding the tissue site 104. The apertures 160 may provide sufficient contact of the adhesive 136 to the epidermis 106 to secure the dressing 124 about the tissue site 104. However, the configuration of the apertures 160 and the adhesive 136, described below, may permit release and repositioning of the dressing 124 about the tissue site 104.

At least one of the apertures 160 a in the periphery 152 of the base layer 132 may be positioned at the edges 159 of the periphery 152 and may have an interior cut open or exposed at the edges 159 that is in fluid communication in a lateral direction with the edges 159. The lateral direction may refer to a direction toward the edges 159 and in the same plane as the base layer 132. As shown in FIGS. 4A-4B, a plurality of the apertures 160 a in the periphery 152 may be positioned proximate to or at the edges 159 and in fluid communication in a lateral direction with the edges 159. The apertures 160 a positioned proximate to or at the edges 159 may be spaced substantially equidistant around the periphery 152 as shown in FIGS. 4A-4B. However, in some embodiments, the spacing of the apertures 160 a proximate to or at the edges 159 may be irregular. The adhesive 136 may be in fluid communication with the edges 159 through the apertures 160 a being exposed at the edges 159. In this manner, the apertures 160 a at the edges 159 may permit the adhesive 136 to flow around the edges 159 for enhancing the adhesion of the edges 159 around the tissue site 104, for example.

Continuing with FIGS. 4A-4B, the apertures 160 b at the corners 158 of the periphery 152 may be smaller than the apertures 160 a in other portions of the periphery 152 as described above. For a given geometry of the corners 158, the smaller size of the apertures 160 b compared to the apertures 160 a may maximize the surface area of the adhesive 136 exposed and in fluid communication through the apertures 160 b at the corners 158. For example, as shown in FIGS. 4A-4B, the edges 159 may intersect at substantially a right angle, or about 90 degrees, to define the corners 158. Also as shown, the corners 158 may have a radius of about 10 millimeters. Three of the apertures 160 b having a diameter between about 7.75 millimeters to about 8.75 millimeters may be positioned in a triangular configuration at the corners 158 to maximize the exposed surface area for the adhesive 136. The size and number of the apertures 160 b in the corners 158 may be adjusted as necessary, depending on the chosen geometry of the corners 158, to maximize the exposed surface area of the adhesive 136 as described above. Further, the apertures 160 b at the corners 158 may be fully housed within the base layer 132, substantially precluding fluid communication in a lateral direction exterior to the corners 158. The apertures 160 b at the corners 158 being fully housed within the base layer 132 may substantially preclude fluid communication of the adhesive 136 exterior to the corners 159, and may provide improved handling of the dressing 124 during deployment at the tissue site 104. Further, the exterior of the corners 158 being substantially free of the adhesive 136 may increase the flexibility of the corners 158 to enhance comfort.

Similar to the apertures 160 b in the corners 158, any of the apertures 160 may be adjusted in size and number to maximize the surface area of the adhesive 136 in fluid communication through the apertures 160 for a particular application or geometry of the base layer 132. For example, in some embodiments (not shown) the apertures 160 b, or apertures of another size, may be positioned in the periphery 152 and at the border 161. Similarly, the apertures 160 b, or apertures of another size, may be positioned as described above in other locations of the base layer 132 that may have a complex geometry or shape.

The adhesive 136 may be a medically-acceptable adhesive. The adhesive 136 may also be flowable. For example, the adhesive 136 may comprise an acrylic adhesive, rubber adhesive, high-tack silicone adhesive, polyurethane, or other adhesive substance. In some embodiments, the adhesive 136 may be a pressure-sensitive adhesive comprising an acrylic adhesive with coating weight of 15 grams/m² (gsm) to 70 grams/m² (gsm). The adhesive 136 may be a layer having substantially the same shape as the periphery 152 of the base layer 132 as shown in FIG. 4A. In some embodiments, the layer of the adhesive 136 may be continuous or discontinuous. Discontinuities in the adhesive 136 may be provided by apertures (not shown) in the adhesive 136. The apertures in the adhesive 136 may be formed after application of the adhesive 136 or by coating the adhesive 136 in patterns on a carrier layer, such as, for example, a side of the sealing member 140 adapted to face the epidermis 106. Further, the apertures in the adhesive 136 may be sized to control the amount of the adhesive 136 extending through the apertures 160 in the base layer 132 to reach the epidermis 106. The apertures in the adhesive 136 may also be sized to enhance the Moisture Vapor Transfer Rate (MVTR) of the dressing 124, described further below.

Factors that may be utilized to control the adhesion strength of the dressing 124 may include the diameter and number of the apertures 160 in the base layer 132, the thickness of the base layer 132, the thickness and amount of the adhesive 136, and the tackiness of the adhesive 136. An increase in the amount of the adhesive 136 extending through the apertures 160 generally corresponds to an increase in the adhesion strength of the dressing 124. A decrease in the thickness of the base layer 132 generally corresponds to an increase in the amount of adhesive 136 extending through the apertures 160. Thus, the diameter and configuration of the apertures 160, the thickness of the base layer 132, and the amount and tackiness of the adhesive utilized may be varied to provide a desired adhesion strength for the dressing 124. For example, the thickness of the base layer 132 may be about 200 microns, the adhesive layer 136 may have a thickness of about 30 microns and a tackiness of 2000 grams per 25 centimeter wide strip, and the diameter of the apertures 160 a in the base layer 132 may be about 10 millimeters.

In some embodiments, the tackiness of the adhesive 136 may vary in different locations of the base layer 132. For example, in locations of the base layer 132 where the apertures 160 are comparatively large, such as the apertures 160 a, the adhesive 136 may have a lower tackiness than other locations of the base layer 132 where the apertures 160 are smaller, such as the apertures 160 b and 160 c. In this manner, locations of the base layer 132 having larger apertures 160 and lower tackiness adhesive 136 may have an adhesion strength comparable to locations having smaller apertures 160 and higher tackiness adhesive 136.

Clinical studies have shown that the configuration described herein for the base layer 132 and the adhesive 136 may reduce the occurrence of blistering, erythema, and leakage when in use. Such a configuration may provide, for example, increased patient comfort and increased durability of the dressing 124.

Referring to the embodiment of FIG. 4B, a release liner 162 may be attached to or positioned adjacent to the base layer 132 to protect the adhesive 136 prior to application of the dressing 124 to the tissue site 104. Prior to application of the dressing 124 to the tissue site 104, the base layer 132 may be positioned between the sealing member 140 and the release liner 162. Removal of the release liner 162 may expose the base layer 132 and the adhesive 136 for application of the dressing 124 to the tissue site 104. The release liner 162 may also provide stiffness to assist with, for example, deployment of the dressing 124. The release liner 162 may be, for example, a casting paper, a film, or polyethylene. Further, the release liner 162 may be a polyester material such as polyethylene terephthalate (PET), or similar polar semi-crystalline polymer. The use of a polar semi-crystalline polymer for the release liner 162 may substantially preclude wrinkling or other deformation of the dressing 124. For example, the polar semi-crystalline polymer may be highly orientated and resistant to softening, swelling, or other deformation that may occur when brought into contact with components of the dressing 124, or when subjected to temperature or environmental variations, or sterilization. Further, a release agent may be disposed on a side of the release liner 162 that is configured to contact the base layer 132. For example, the release agent may be a silicone coating and may have a release factor suitable to facilitate removal of the release liner 162 by hand and without damaging or deforming the dressing 124. In some embodiments, the release agent may be flourosilicone. In other embodiments, the release liner 162 may be uncoated or otherwise used without a release agent.

Continuing with FIGS. 1-4B, the sealing member 140 has a periphery 164 and a central portion 168. The sealing member 140 may additionally include an aperture 170, as described below. The periphery 164 of the sealing member 140 may be positioned proximate to the periphery 152 of the base layer 132 such that the central portion 168 of the sealing member 140 and the central portion 156 of the base layer 132 define an enclosure 172. The adhesive 136 may be positioned at least between the periphery 164 of the sealing member 140 and the periphery 152 of the base layer 132. The sealing member 140 may cover the tissue site 104 and the interface manifold 120 to provide a fluid seal and a sealed space 174 between the tissue site 104 and the sealing member 140 of the dressing 124. Further, the sealing member 140 may cover other tissue, such as a portion of the epidermis 106, surrounding the tissue site 104 to provide the fluid seal between the sealing member 140 and the tissue site 104. In some embodiments, a portion of the periphery 164 of the sealing member 140 may extend beyond the periphery 152 of the base layer 132 and into direct contact with tissue surrounding the tissue site 104. In other embodiments, the periphery 164 of the sealing member 140, for example, may be positioned in contact with tissue surrounding the tissue site 104 to provide the sealed space 174 without the base layer 132. Thus, the adhesive 136 may also be positioned at least between the periphery 164 of the sealing member 140 and tissue, such as the epidermis 106, surrounding the tissue site 104. The adhesive 136 may be disposed on a surface of the sealing member 140 adapted to face the tissue site 104 and the base layer 132.

The sealing member 140 may be formed from any material that allows for a fluid seal. A fluid seal is a seal adequate to maintain reduced pressure at a desired site given the particular reduced pressure source or system involved. The sealing member 140 may comprise, for example, one or more of the following materials: hydrophilic polyurethane; cellulosics; hydrophilic polyamides; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic acrylics; hydrophilic silicone elastomers; an INSPIRE 2301 material from Expopack Advanced Coatings of Wrexham, United Kingdom having, for example, an MVTR (inverted cup technique) of 14400 g/m²/24 hours and a thickness of about 30 microns; a thin, uncoated polymer drape; natural rubbers; polyisoprene; styrene butadiene rubber; chloroprene rubber; polybutadiene; nitrile rubber; butyl rubber; ethylene propylene rubber; ethylene propylene diene monomer; chlorosulfonated polyethylene; polysulfide rubber; polyurethane (PU); EVA film; co-polyester; silicones; a silicone drape; a 3M Tegaderm® drape; a polyurethane (PU) drape such as one available from Avery Dennison Corporation of Pasadena, Calif.; polyether block polyamide copolymer (PEBAX), for example, from Arkema, France; Expopack 2327; or other appropriate material.

The sealing member 140 may be vapor permeable and liquid impermeable, thereby allowing vapor and inhibiting liquids from exiting the sealed space 174 provided by the dressing 124. In some embodiments, the sealing member 140 may be a flexible, breathable film, membrane, or sheet having a high MVTR of, for example, at least about 300 g/m² per 24 hours. In other embodiments, a low or no vapor transfer drape might be used. The sealing member 140 may comprise a range of medically suitable films having a thickness between about 15 microns (μm) to about 50 microns (μm).

The fluid management assembly 144 may be disposed in the enclosure 172 and may include a first wicking layer 176, a second wicking layer 180, and an absorbent layer 184. The absorbent layer 184 may be positioned in fluid communication between the first wicking layer 176 and the second wicking layer 180. The first wicking layer 176 may have a grain structure (not shown) adapted to wick fluid along a surface of the first wicking layer 176. Similarly, the second wicking layer 180 may have a grain structure (not shown) adapted to wick fluid along a surface of the second wicking layer 180. For example, the first wicking layer 176 and the second wicking layer 180 may wick or otherwise transport fluid in a lateral direction along the surfaces of the first wicking layer 176 and the second wicking layer 180, respectively. The surfaces of the first wicking layer 176 and the second wicking layer 180 may be normal relative to the thickness of each of the first wicking layer 176 and the second wicking layer 180. The wicking of fluid along the first wicking layer 176 and the second wicking layer 180 may enhance the distribution of the fluid over a surface area of the absorbent layer 184 that may increase absorbent efficiency and resist fluid blockages. Fluid blockages may be caused by, for example, fluid pooling in a particular location in the absorbent layer 184 rather than being distributed more uniformly across the absorbent layer 184. The laminate combination of the first wicking layer 176, the second wicking layer 180, and the absorbent layer 184 may be adapted as described above to maintain an open structure, resistant to blockage, capable of maintaining fluid communication with, for example, the tissue site 104.

Referring to the embodiments of the fluid management assembly 144 depicted in FIGS. 1, 2, 5, and 6 , a peripheral portion 186 of the first wicking layer 176 may be coupled to a peripheral portion 187 of the second wicking layer 180 to define a wicking layer enclosure 188 between the first wicking layer 176 and the second wicking layer 180. In some exemplary embodiments, the wicking layer enclosure 188 may surround or otherwise encapsulate the absorbent layer 184 between the first wicking layer 176 and the second wicking layer 180.

Referring specifically to FIGS. 5 and 6 , the fluid management assembly 144 may include, without limitation, any number of wicking layers and absorbent layers as desired for treating a particular tissue site. For example, the absorbent layer 184 may be a plurality of absorbent layers 184 positioned in fluid communication between the first wicking layer 176 and the second wicking layer 180 as described above. Further, as depicted in FIG. 6 , at least one intermediate wicking layer 189 may be disposed in fluid communication between the plurality of absorbent layers 184. Similar to the absorbent layer 184 described above, the plurality of absorbent layers 184 and the at least one intermediate wicking layer 189 may be positioned within the wicking layer enclosure 188. In some embodiments, the absorbent layer 184 may be disposed between the sealing member 140 and the interface manifold 120, and the first wicking layer 176 and the second wicking layer 180 may be omitted.

In the embodiments of FIGS. 5 and 6 , sides 184 a of the absorbent layers 184 may remain in fluid communication with one another for enhancing efficiency. Similarly, in the embodiment of FIG. 6 , sides 189 a of the at least one intermediate wicking layer 189 may remain in fluid communication with one another and with the sides 184 a of the absorbent layers 184. Further, including additional absorbent layers 184 may increase the absorbent mass of the fluid management assembly 144 and generally provide greater fluid capacity. However, for a given absorbent mass, multiple light coat-weight absorbent layers 184 may be utilized rather than a single heavy coat-weight absorbent layer 184 to provide a greater absorbent surface area for further enhancing the absorbent efficiency.

In some embodiments, the absorbent layer 184 may be a hydrophilic material adapted to absorb fluid from, for example, the tissue site 104. Materials suitable for the absorbent layer 184 may include Luquafleece® material, Texsus FP2326, BASF 402C, Technical Absorbents 2317 available from Technical Absorbents (www.techabsorbents.com), sodium polyacrylate super absorbers, cellulosics (carboxy methyl cellulose and salts such as sodium CMC), or alginates. Materials suitable for the first wicking layer 176 and the second wicking layer 180 may include any material having a grain structure capable of wicking fluid as described herein, such as, for example, Libeltex TDL2 80 gsm.

The fluid management assembly 144 may be a pre-laminated structure manufactured at a single location or individual layers of material stacked upon one another as described above. Individual layers of the fluid management assembly 144 may be bonded or otherwise secured to one another without adversely affecting fluid management by, for example, utilizing a solvent or non-solvent adhesive, or by thermal welding. Further, the fluid management assembly 144 may be coupled to the border 161 of the base layer 132 in any suitable manner, such as, for example, by a weld or an adhesive. The border 161 being free of the apertures 160 as described above may provide a flexible barrier between the fluid management assembly 144 and the tissue site 104 for enhancing comfort.

In some embodiments, the enclosure 172 defined by the base layer 132 and the sealing member 140 may include an anti-microbial layer 190. The addition of the anti-microbial layer 190 may reduce the probability of excessive bacterial growth within the dressing 124 to permit the dressing 124 to remain in place for an extended period. The anti-microbial layer 190 may be, for example, an additional layer included as a part of the fluid management assembly 144 as depicted in FIGS. 1 and 2 , or a coating of an anti-microbial agent disposed in any suitable location within the dressing 124. The anti-microbial layer 190 may be comprised of elemental silver or similar compound, for example. In some embodiments, the anti-microbial agent may be formulated in any suitable manner into other components of the dressing 124.

Referring to FIGS. 1, 2, and 7 , the conduit interface 148 may be positioned proximate to the sealing member 140 and in fluid communication with the dressing 124 through the aperture 170 in the sealing member 140 to provide reduced pressure from the reduced-pressure source 128 to the dressing 124. Specifically, the conduit interface 148 may be positioned in fluid communication with the enclosure 172 of the dressing 124. The conduit interface 148 may also be positioned in fluid communication with the optional interface manifold 120. As shown, an optional liquid trap 192 may be positioned in fluid communication between the dressing 124 and the reduced-pressure source 128. The liquid trap 192 may be any suitable containment device having a sealed internal volume capable of retaining liquid, such as condensate or other liquids, as described below.

The conduit interface 148 may comprise a medical-grade, soft polymer or other pliable material. As non-limiting examples, the conduit interface 148 may be formed from polyurethane, polyethylene, polyvinyl chloride (PVC), fluorosilicone, or ethylene-propylene, etc. In some illustrative, non-limiting embodiments, conduit interface 148 may be molded from DEHP-free PVC. The conduit interface 148 may be formed in any suitable manner such as by molding, casting, machining, or extruding. Further, the conduit interface 148 may be formed as an integral unit or as individual components and may be coupled to the dressing 124 by, for example, adhesive or welding.

In some embodiments, the conduit interface 148 may be formed of an absorbent material having absorbent and evaporative properties. The absorbent material may be vapor permeable and liquid impermeable, thereby being configured to permit vapor to be absorbed into and evaporated from the material through permeation while inhibiting permeation of liquids. The absorbent material may be, for example, a hydrophilic polymer such as a hydrophilic polyurethane. Although the term hydrophilic polymer may be used in the illustrative embodiments that follow, any absorbent material having the properties described herein may be suitable for use in the system 102. Further, the absorbent material or hydrophilic polymer may be suitable for use in various components of the system 102 as described herein.

The use of such a hydrophilic polymer for the conduit interface 148 may permit liquids in the conduit interface 148 to evaporate, or otherwise dissipate, during operation. For example, the hydrophilic polymer may allow the liquid to permeate or pass through the conduit interface 148 as vapor, in a gaseous phase, and evaporate into the atmosphere external to the conduit interface 148. Such liquids may be, for example, condensate or other liquids. Condensate may form, for example, as a result of a decrease in temperature within the conduit interface 148, or other components of the system 102, relative to the temperature at the tissue site 104. Removal or dissipation of liquids from the conduit interface 148 may increase visual appeal and prevent odor. Further, such removal of liquids may also increase efficiency and reliability by reducing blockages and other interference with the components of the system 102.

Similar to the conduit interface 148, the liquid trap 192, and other components of the system 102 described herein, may also be formed of an absorbent material or a hydrophilic polymer. The absorptive and evaporative properties of the hydrophilic polymer may also facilitate removal and dissipation of liquids residing in the liquid trap 192, and other components of the system 102, by evaporation. Such evaporation may leave behind a substantially solid or gel-like waste. The substantially solid or gel-like waste may be cheaper to dispose than liquids, providing a cost savings for operation of the system 102. The hydrophilic polymer may be used for other components in the system 102 where the management of liquids is beneficial.

In some embodiments, the absorbent material or hydrophilic polymer may have an absorbent capacity in a saturated state that is substantially equivalent to the mass of the hydrophilic polymer in an unsaturated state. The hydrophilic polymer may be fully saturated with vapor in the saturated state and substantially free of vapor in the unsaturated state. In both the saturated state and the unsaturated state, the hydrophilic polymer may retain substantially the same physical, mechanical, and structural properties. For example, the hydrophilic polymer may have a hardness in the unsaturated state that is substantially the same as a hardness of the hydrophilic polymer in the saturated state. The hydrophilic polymer and the components of the system 102 incorporating the hydrophilic polymer may also have a size that is substantially the same in both the unsaturated state and the saturated state. Further, the hydrophilic polymer may remain dry, cool to the touch, and pneumatically sealed in the saturated state and the unsaturated state. The hydrophilic polymer may also remain substantially the same color in the saturated state and the unsaturated state. In this manner, this hydrophilic polymer may retain sufficient strength and other physical properties to remain suitable for use in the system 102. An example of such a hydrophilic polymer is offered under the trade name Techophilic HP-93A-100, available from The Lubrizol Corporation of Wickliffe, Ohio, United States. Techophilic HP-93A-100 is an absorbent hydrophilic thermoplastic polyurethane capable of absorbing 100% of the unsaturated mass of the polyurethane in water and having a durometer or Shore Hardness of about 83 Shore A.

The conduit interface 148 may carry an odor filter 194 adapted to substantially preclude the passage of odors from the tissue site 104 out of the sealed space 174. Further, the conduit interface 148 may carry a primary hydrophobic filter 195 adapted to substantially preclude the passage of liquids out of the sealed space 174. The odor filter 194 and the primary hydrophobic filter 195 may be disposed in the conduit interface 148 or other suitable location such that fluid communication between the reduced-pressure source 128, or optional therapy unit 130, and the dressing 124 is provided through the odor filter 194 and the primary hydrophobic filter 195. In some embodiments, the odor filter 194 and the primary hydrophobic filter 195 may be secured within the conduit interface 148 in any suitable manner, such as by adhesive or welding. In other embodiments, the odor filter 194 and the primary hydrophobic filter 195 may be positioned in any exit location in the dressing 124 that is in fluid communication with the atmosphere, the reduced-pressure source 128, or the optional therapy unit 130. The odor filter 194 may also be positioned in any suitable location in the system 102 that is in fluid communication with the tissue site 104.

The odor filter 194 may be comprised of a carbon material in the form of a layer or particulate. For example, the odor filter 194 may comprise a woven carbon cloth filter such as those manufactured by Chemviron Carbon, Ltd. of Lancashire, United Kingdom (www.chemvironcarbon.com). The primary hydrophobic filter 195 may be comprised of a material that is liquid impermeable and vapor permeable. For example, the primary hydrophobic filter 195 may comprise a material manufactured under the designation MMT-314 by W.L. Gore & Associates, Inc. of Newark, Del., United States, or similar materials. The primary hydrophobic filter 195 may be provided in the form of a membrane or layer.

Continuing with FIGS. 1, 2, and 7 , the reduced-pressure source 128 provides reduced pressure to the dressing 124 and the sealed space 174. The reduced-pressure source 128 may be any suitable device for providing reduced pressure, such as, for example, a vacuum pump, wall suction, hand pump, or other source. As shown in FIG. 1 , the reduced-pressure source 128 may be a component of the therapy unit 130. The therapy unit 130 may include control circuitry and sensors, such as a pressure sensor, that may be configured to monitor reduced pressure at the tissue site 104. The therapy unit 130 may also be configured to control the amount of reduced pressure from the reduced-pressure source 128 being applied to the tissue site 104 according to a user input and a reduced-pressure feedback signal received from the tissue site 104.

As used herein, “reduced pressure” generally refers to a pressure less than the ambient pressure at a tissue site being subjected to treatment. Typically, this reduced pressure will be less than the atmospheric pressure. The reduced pressure may also be less than a hydrostatic pressure at a tissue site. Unless otherwise indicated, values of pressure stated herein are gauge pressures. While the amount and nature of reduced pressure applied to a tissue site will typically vary according to the application, the reduced pressure will typically be between −5 mm Hg and −500 mm Hg, and more typically in a therapeutic range between −100 mm Hg and −200 mm Hg.

The reduced pressure delivered may be constant or varied (patterned or random), and may be delivered continuously or intermittently. Although the terms “vacuum” and “negative pressure” may be used to describe the pressure applied to the tissue site, the actual pressure applied to the tissue site may be more than the pressure normally associated with a complete vacuum. Consistent with the use herein, an increase in reduced pressure or vacuum pressure typically refers to a relative reduction in absolute pressure. An increase in reduced pressure corresponds to a reduction in pressure (more negative relative to ambient pressure) and a decrease in reduced pressure corresponds to an increase in pressure (less negative relative to ambient pressure).

As shown in FIG. 7 , a conduit 196 having an internal lumen 197 may be coupled in fluid communication between the reduced-pressure source 128 and the dressing 124. The internal lumen 197 may have an internal diameter between about 0.5 millimeters to about 3.0 millimeters. More specifically, the internal diameter of the internal lumen 197 may be between about 1 millimeter to about 2 millimeters. The conduit interface 148 may be coupled in fluid communication with the dressing 124 and adapted to connect between the conduit 196 and the dressing 124 for providing fluid communication with the reduced-pressure source 128. The conduit interface 148 may be fluidly coupled to the conduit 196 in any suitable manner, such as, for example, by an adhesive, solvent or non-solvent bonding, welding, or interference fit. The aperture 170 in the sealing member 140 may provide fluid communication between the dressing 124 and the conduit interface 148. Specifically, the conduit interface 148 may be in fluid communication with the enclosure 172 or the sealed space 174 through the aperture 170 in the sealing member 140. In some embodiments, the conduit 196 may be inserted into the dressing 124 through the aperture 170 in the sealing member 140 to provide fluid communication with the reduced-pressure source 128 without use of the conduit interface 148. The reduced-pressure source 128 may also be directly coupled in fluid communication with the dressing 124 or the sealing member 140 without use of the conduit 196. The conduit 196 may be, for example, a flexible polymer tube. A distal end of the conduit 196 may include a coupling 198 for attachment to the reduced-pressure source 128.

The conduit 196 may have a secondary hydrophobic filter 199 disposed in the internal lumen 197 such that fluid communication between the reduced-pressure source 128 and the dressing 124 is provided through the secondary hydrophobic filter 199. The secondary hydrophobic filter 199 may be, for example, a porous, sintered polymer cylinder sized to fit the dimensions of the internal lumen 197 to substantially preclude liquid from bypassing the cylinder. The secondary hydrophobic filter 199 may also be treated with an absorbent material adapted to swell when brought into contact with liquid to block the flow of the liquid. The secondary hydrophobic filter 199 may be positioned at any location within the internal lumen 197. However, positioning the secondary hydrophobic filter 199 within the internal lumen 197 closer toward the reduced-pressure source 128, rather than the dressing 124, may allow a user to detect the presence of liquid in the internal lumen 197.

In some embodiments, the conduit 196 and the coupling 198 may be formed of an absorbent material or a hydrophilic polymer as described above for the conduit interface 148. In this manner, the conduit 196 and the coupling 198 may permit liquids in the conduit 196 and the coupling 198 to evaporate, or otherwise dissipate, as described above for the conduit interface 148. The conduit 196 and the coupling 198 may be, for example, molded from the hydrophilic polymer separately, as individual components, or together as an integral component. Further, a wall of the conduit 196 defining the internal lumen 197 may be extruded from the hydrophilic polymer. The conduit 196 may be less than about 1 meter in length, but may have any length to suit a particular application. More specifically, a length of about 1 foot or 304.8 millimeters may provide enough absorbent and evaporative surface area to suit many applications, and may provide a cost savings compared to longer lengths. If an application requires additional length for the conduit 196, the absorbent hydrophilic polymer may be coupled in fluid communication with a length of conduit formed of a non-absorbent hydrophobic polymer to provide additional cost savings.

Referring now to FIG. 8 , FIG. 8 depicts the dressing 124 including a fluid management assembly 244 suitable for use with the dressing 124 and the system 102. The fluid management assembly 244 may include a first wicking layer 276, a second wicking layer 280, and an absorbent layer 284 comprised of substantially the same materials and properties as those described above in connection with the fluid management assembly 144. Thus, the first wicking layer 276, the second wicking layer 280, and the absorbent layer 284 are analogous to the first wicking layer 176, the second wicking layer 180, and the absorbent layer 184, respectively.

In the fluid management assembly 244, the second wicking layer 280 may have a peripheral portion 287. The second wicking layer 280 and the peripheral portion 287 of the second wicking layer 280 may be positioned in contact with the sealing member 140. The absorbent layer 284 may have a peripheral portion 285 extending beyond the peripheral portion 287 of the second wicking layer 280. The absorbent layer 284 may be positioned adjacent to or proximate to the second wicking layer 280 such that the peripheral portion 285 of the absorbent layer 284 is in contact with the sealing member 140 surrounding the peripheral portion 287 of the second wicking layer 280. Similarly, the first wicking layer 276 may have a peripheral portion 286 extending beyond the peripheral portion 285 of the absorbent layer 284. The first wicking layer 276 may be positioned adjacent to or proximate to the absorbent layer 284 such that the peripheral portion 286 of the first wicking layer 276 is in contact with the sealing member 140 surrounding the peripheral portion 285 of the absorbent layer 284. Further, the first wicking layer 276 may be positioned adjacent to or proximate to the base layer 132. Thus, at least the peripheral portion 287, the peripheral portion 285, and the peripheral portion 286 in contact with the sealing member 140 may be coupled to the sealing member 140, such as, for example, by an adhesive coating disposed on a surface of the sealing member 140 facing the base layer 132. The adhesive coating may be analogous to the adhesive 136 being applied across the surface of the sealing member 140 facing the base layer 132. The second wicking layer 280, the absorbent layer 284, and the first wicking layer 276 may respectively have increasing surface areas to enhance contact with the adhesive coating described above. In other embodiments, the fluid management assembly 244 may include any number of absorbent layers and wicking layers for treating a particular tissue site.

In operation of the system 102 according to some illustrative embodiments, the interface manifold 120 may be disposed against or proximate to the tissue site 104. The dressing 124 may then be applied over the interface manifold 120 and the tissue site 104 to form the sealed space 174. Specifically, the base layer 132 may be applied covering the interface manifold 120 and the tissue surrounding the tissue site 104. The materials described above for the base layer 132 have a tackiness that may hold the dressing 124 initially in position. The tackiness may be such that if an adjustment is desired, the dressing 124 may be removed and reapplied. Once the dressing 124 is in the desired position, a force may be applied, such as by hand pressing, on a side of the sealing member 140 opposite the tissue site 104. The force applied to the sealing member 140 may cause at least some portion of the adhesive 136 to penetrate or extend through the plurality of apertures 160 and into contact with tissue surrounding the tissue site 104, such as the epidermis 106, to releasably adhere the dressing 124 about the tissue site 104. In this manner, the configuration of the dressing 124 described above may provide an effective and reliable seal against challenging anatomical surfaces, such as an elbow or heal, at and around the tissue site 104. Further, the dressing 124 permits re-application or re-positioning to, for example, correct air leaks caused by creases and other discontinuities in the dressing 124 and the tissue site 104. The ability to rectify leaks may increase the reliability of the therapy and reduce power consumption.

As the dressing 124 comes into contact with fluid from the tissue site 104, the fluid moves through the apertures 160 toward the fluid management assembly 144, 244. The fluid management assembly 144, 244 wicks or otherwise moves the fluid through the interface manifold 120 and away from the tissue site 104. As described above, the interface manifold 120 may be adapted to communicate fluid from the tissue site 104 rather than store the fluid. Thus, the fluid management assembly 144, 244 may be more absorbent than the interface manifold 120. The fluid management assembly 144, 244 being more absorbent than the interface manifold 120 provides an absorbent gradient through the dressing 124 that attracts fluid from the tissue site 104 or the interface manifold 120 to the fluid management assembly 144, 244. Thus, in some embodiments, the fluid management assembly 144, 244 may be adapted to wick, pull, draw, or otherwise attract fluid from the tissue site 104 through the interface manifold 120. In the fluid management assembly 144, 244, the fluid initially comes into contact with the first wicking layer 176, 276. The first wicking layer 176, 276 may distribute the fluid laterally along the surface of the first wicking layer 176, 276 as described above for absorption and storage within the absorbent layer 184, 284. Similarly, fluid coming into contact with the second wicking layer 180, 280 may be distributed laterally along the surface of the second wicking layer 180, 280 for absorption within the absorbent layer 184, 284.

Referring to FIGS. 9A-9E, in other embodiments, the conduit 196 may be a multi-lumen conduit 302. For example, FIG. 9A depicts an illustrative embodiment of a multi-lumen conduit 302 a. The multi-lumen conduit 302 a may have an external surface 306, a primary lumen 310, a wall 314, and at least one secondary lumen 318. The wall 314 may carry the primary lumen 310 and the at least one secondary lumen 318. The primary lumen 310 may be substantially isolated from fluid communication with the at least one secondary lumen 318 along the length of the multi-lumen conduit 302 a. Although shown in FIG. 9A as having a substantially circular cross-section, the external surface 306 of the multi-lumen conduit 302 a may have any shape to suit a particular application. The wall 314 of the multi-lumen conduit 302 a may have a thickness between the primary lumen 310 and the external surface 306. As depicted in FIG. 9A, the at least one secondary lumen 318 may be four secondary lumens 318 carried by the wall 314 substantially parallel to the primary lumen 310 and about a perimeter of the primary lumen 310. The secondary lumens 318 may be separate from one another and substantially isolated from fluid communication with one another along the length of the multi-lumen conduit 302 a. Further, the secondary lumens 318 may be separate from the primary lumen 310 and substantially isolated from fluid communication with the primary lumen 310. The secondary lumens 318 may also be positioned concentric relative to the primary lumen 310 and substantially equidistant about the perimeter of the primary lumen 310. Although FIG. 9A depicts four secondary lumens 318, any number of secondary lumens 318 may be provided and positioned in any suitable manner for a particular application.

Similar to the internal lumen 197 of the conduit 196, the primary lumen 310 may be coupled in fluid communication between the reduced-pressure source 128 and the dressing 124 as described above. In some embodiments, the primary lumen 310 may be coupled in fluid communication between the conduit interface 148 and the reduced-pressure source 128. Further, analogous to the internal lumen 197, reduced pressure may be provided through the primary lumen 310 from the reduced-pressure source 128 to the dressing 124. In some embodiments, the primary lumen 310 may be configured to extract fluid such as exudate from the tissue site 104. The secondary lumens 318 may be coupled in fluid communication between the therapy unit 130 and the dressing 124. In some embodiments, the at least one secondary lumen 318 may be coupled in fluid communication between the conduit interface 148 and the therapy unit 130. Further, the secondary lumens 318 may be in fluid communication with the primary lumen 310 at the dressing 124 and configured to provide a reduced-pressure feedback signal from the dressing 124 to the therapy unit 130. For example, the secondary lumens 318 may be in fluid communication with the primary lumen 310 at the conduit interface 148 or other component of the dressing 124.

The multi-lumen conduit 302 a may be comprised of an absorbent material or hydrophilic polymer, such as, for example, the absorbent material or the hydrophilic polymer described above in connection with the conduit interface 148, the conduit 196, and the coupling 198. The absorbent material or the hydrophilic polymer may be vapor permeable and liquid impermeable. In some embodiments, at least a portion of the wall 314 and the external surface 306 of the multi-lumen conduit 302 a may be comprised of the absorbent material or the hydrophilic polymer. In this manner, the multi-lumen conduit 302 a may permit liquids, such as condensate, in the multi-lumen conduit 302 a to evaporate, or otherwise dissipate, as described above. For example, the absorbent material or the hydrophilic polymer may allow the liquid to pass through the multi-lumen conduit 302 a as vapor, in a gaseous phase, and evaporate into the atmosphere external to the multi-lumen conduit 302 a. Liquids such as exudate from the tissue site 104 may also be evaporated or dissipated through the multi-lumen conduit 302 a in the same manner. This feature may be advantageous when the optional therapy unit 130 is used for monitoring and controlling reduced pressure at the tissue site 104. For example, liquid present in the secondary lumens 318 may interfere with a reduced-pressure feedback signal being transmitted to the therapy unit 130 through the secondary lumens 318. The use of the hydrophilic polymer for the multi-lumen conduit 302 a may permit removal of such liquid for enhancing the visual appeal, reliability, and efficiency of the system 102. After evaporation of liquid in the multi-lumen conduit 302 a, other blockages from, for example, desiccated exudate, solids, or gel-like substances that were carried by the evaporated liquid may be visible for further remediation. Further, the use of the hydrophilic polymer as described herein may reduce the occurrence of skin damage caused by moisture buildup between components of the system 102, such as the multi-lumen conduit 302 a, and the skin of a patient.

Depicted in FIG. 9B is another illustrative embodiment of a multi-lumen conduit 302 b. Similar to the multi-lumen conduit 302 a, the multi-lumen conduit 302 b may have the external surface 306, the primary lumen 310, the wall 314, and the at least one secondary lumen 318 as described above. However, the wall 314 of the multi-lumen conduit 302 b may include a first wall material 314 a and a second wall material 314 b. The first wall material 314 a and the second wall material 314 b may be comprised of different materials to form the wall 314. For example, the first wall material 314 a may comprise a substantially non-absorbent hydrophobic polymer, or other material, that is vapor impermeable and liquid impermeable. The first wall material 314 a may completely surround the primary lumen 310, defining the primary lumen 310 as shown in FIG. 9B. In some embodiments (not shown), the first wall material 314 a may be positioned around the primary lumen 310 without completely surrounding or defining the primary lumen 310. The second wall material 314 b may comprise the same absorbent material or hydrophilic polymer described above for the multi-lumen conduit 302 a as being vapor permeable and liquid impermeable. As shown in FIG. 9B, the second wall material 314 b may be positioned in fluid contact with the at least one secondary lumen 318. The second wall material 314 b may also define the at least one secondary lumen 318 and at least a portion of the external surface 306 of the multi-lumen conduit 302 b. In some embodiments (not shown), the second wall material 314 b may substantially surround the at least one secondary lumen 318 without completely defining the secondary lumen 318.

Continuing with FIG. 9B, the first wall material 314 a may be substantially concentric about the primary lumen 310, and the second wall material 314 b may be substantially concentric about and contiguous with the first wall material 314 a. The first wall material 314 a and the second wall material 314 b may be molded, co-extruded, or otherwise combined with one another in any suitable manner to form the wall 314. The wall 314, including the first wall material 314 a and the second wall material 314 b, may provide a cost savings while retaining the absorbent and evaporative properties of the hydrophilic polymer for remediating liquid in the multi-lumen conduit 302 b and the at least one secondary lumen 318. Further, the use of the first wall material 314 a as described herein may provide sufficient strength and other physical properties for the multi-lumen conduit 302 b to remain serviceable under reduced pressure in the system 102 without regard to the physical properties of second wall material 314 b. For example, the use of a non-absorbent hydrophobic polymer for the first wall material 314 a may permit the use of absorbent hydrophilic polymers for the second wall material 314 b that may not otherwise have sufficient strength for use under reduced pressure in the system 102.

The first wall material 314 a may be combined with the second wall material 314 b to form the wall 314 in various configurations for remediating liquid in the multi-lumen conduit 302 and the at least one secondary lumen 318. For example, referring to FIG. 9C, depicted is an illustrative embodiment of a multi-lumen conduit 302 c. Similar to the multi-lumen conduits 302 a and 302 b, the multi-lumen conduit 302 c may have the external surface 306, the primary lumen 310, the wall 314, and the at least one secondary lumen 318. As shown in FIG. 9C, the wall 314 of the multi-lumen conduit 302 c may include the first wall material 314 a positioned around the primary lumen 310 and the second wall material 314 b disposed in separate portions around each of the secondary lumens 318. In this configuration, for example, the external surface 306 may comprise both the first wall material 314 a and the second wall material 314 b. Also as shown in FIG. 9C, the first wall material 314 a may completely surround the primary lumen 310. The second wall material 314 b may be disposed as portions separate from one another and separate from the primary lumen in a radial configuration about the perimeter of the primary lumen 310. However, in some embodiments, the second wall material 314 b may be in fluid contact with the primary lumen 310 and may form a portion of the external surface 306. The amount of the second wall material 314 b surrounding the secondary lumens 318 may be increased or decreased to suit a particular application depending, for example, on the amount of liquid anticipated to be present and the desired mechanical properties of the multi-lumen conduit 302 c.

Continuing with FIG. 9C, the first wall material 314 a may have a receptor 320 configured to receive the second wall material 314 b. The second wall material 314 b surrounding the secondary lumens 318 may have a shape corresponding to the receptor 320 in the first wall material 314 a. For example, each portion of the second wall material 314 b may have a taper 321 a configured to engage a corresponding taper 321 b of the receptor 320. The taper 321 b may be oriented opposite the taper 321 a. As shown in FIG. 9C, the taper 321 b of the receptor 320 may taper from the external surface 306 to a smaller dimension toward the primary lumen 310. The taper 321 a may have a taper opposite the direction of the taper 321 b described above such that the taper 321 b is configured to receive and engage the taper 321 a.

In some embodiments (not shown), the taper 321 a of the second wall material 314 b may taper from the external surface 306 to a larger dimension toward the primary lumen 310. The taper 321 b of the receptor 320 may have a taper opposite the direction of the taper 321 a described above such that the taper 321 b is configured to receive and engage the taper 321 a. In this configuration, with the taper 321 a of the second wall material 314 b having a larger dimension toward the primary lumen 310, the opposite taper 321 b of the receptor 320 may substantially preclude the second wall material 314 b from being pulled away from the receptor 320 in the first wall material 314 a. The above embodiments for the tapers 321 a and 321 b are non-limiting. Other shapes and configurations are suitable for engaging the first wall material 314 a with the second wall material 314 b, such as, for example, interlocking tabs or other mechanical elements.

The multi-lumen conduit 302 may include other materials and configurations for managing liquid in the multi-lumen conduit 302 as described herein. For example, referring to FIG. 9D, depicted is an illustrative embodiment of a multi-lumen conduit 302 d. Similar to the multi-lumen conduits 302 a, 302 b, and 302 c, the multi-lumen conduit 302 d may have the external surface 306, the primary lumen 310, the wall 314, and the at least one secondary lumen 318. The multi-lumen conduit 302 d may additionally include an external absorbent layer 322. The external absorbent layer 322 may be positioned around the wall 314 of the multi-lumen conduit 302 d. The external absorbent layer 322 may be positioned, for example, along the entire length of the multi-lumen conduit 302 d or a portion of the length of the multi-lumen conduit 302 d. More specifically, the external absorbent layer 322 may be positioned on a portion of the length of the multi-lumen conduit 302 d proximate to the dressing 124.

Continuing with FIG. 9D, the wall 314 of the multi-lumen conduit 302 d may comprise an absorbent material or a hydrophilic polymer, such as the absorbent material or the hydrophilic polymer described above for the multi-lumen conduit 302 a as being vapor permeable and liquid impermeable. Although not shown in FIG. 9D, the wall 314 of the multi-lumen conduit 302 d may include the first wall material 314 a and the second wall material 314 b as described above for FIGS. 9B and 9C. The external absorbent layer 322 may be comprised, for example, of the same absorbent material or hydrophilic polymer of the wall 314. In some embodiments, the external absorbent layer 322 may be comprised of a second absorbent material or a second hydrophilic polymer that is vapor permeable and liquid impermeable. The second absorbent material may have a greater absorbent capacity than the absorbent material or hydrophilic polymer comprising the wall 314 or the second wall material 314 b. For example, the second absorbent material of the external absorbent layer 322 may be capable of absorbing more than 100% of the unsaturated mass of the second absorbent material in water. In this manner, the external absorbent layer 322 may be configured to provide an absorptive gradient increasing in absorbent capacity away from the primary lumen 310 and toward the external surface 306. The absorptive gradient may pull, wick, draw, or otherwise attract vapor toward the external surface 306 for evaporation. In some embodiments, the thickness of the wall 314 may be reduced to enhance the passage or permeation of vapor through the wall 314 and to the external atmosphere. In embodiments (not shown) including the first wall material 314 a and the second wall material 314 b, the external absorbent layer 322 may be positioned at least around the second wall material 314 b and in fluid contact with the second wall material 314 b.

Continuing with FIG. 9D, the external surface 306 of the multi-lumen conduit 302 d may have any shape to suit a particular application. For example, the external surface 306 may have a plurality of protrusions 326 and depressions 330 configured to increase the external surface area of the external surface 306. The increased surface area provided by the protrusions 326 and depressions 330 may enhance the ability of the multi-lumen conduit 302 d to evaporate liquids.

Referring to FIG. 9E, depicted is an illustrative embodiment of a multi-lumen conduit 302 e having an oblong cross section. Similar to the multi-lumen conduits 302 a, 302 b, 302 c, and 302 d, the multi-lumen conduit 302 e may have the external surface 306, the primary lumen 310, the wall 314, and the at least one secondary lumen 318. However, FIG. 9E depicts the at least one secondary lumen 318 of the multi-lumen conduit 302 e as a single secondary lumen 318 that may be carried by the wall 314 beside the primary lumen 310. Such a configuration may provide a substantially flat, low profile shape that may enhance user comfort and may increase the flexibility of the multi-lumen conduit 302 e. For example, in this configuration, the multi-lumen conduit 302 e may be routed through tight spaces with reduced risk of kinking or blockages of fluid communication. Although not depicted, additional lumens may be added in this substantially flat configuration, laterally disposed from the primary lumen 310 and the secondary lumen 318, as necessary to suit a particular application.

The above features described in connection with the multi-lumen conduits 302 a, 302 b, 302 c, 302 d, and 302 e may be used in combination with one another to suit a particular application. For example, the external absorbent layer 322 described in the multi-lumen conduit 302 d may be used in combination with any of the multi-lumen conduits 302 a, 302 b, 302 c, and 302 e. Further, any of the multi-lumen conduits 302 a, 302 b, 302 c, 302 d, and 302 e may be used with padding (not shown) disposed around the external surface 306, proximate to the dressing 124, for example, to enhance user comfort.

Although this specification discloses advantages in the context of certain illustrative, non-limiting embodiments, various changes, substitutions, permutations, and alterations may be made without departing from the scope of the appended claims. Further, any feature described in connection with any one embodiment may also be applicable to any other embodiment. 

We claim:
 1. A dressing for treating a tissue site, comprising: a base layer including a plurality of apertures disposed through a periphery and a central portion; and an adhesive configured to extend through the apertures in at least the periphery, at least one of the apertures in a corner of the periphery being configured to expose more of the adhesive for contact with tissue than other apertures in the periphery.
 2. The dressing of claim 1, wherein the apertures in the periphery of the base layer are larger than the apertures in the central portion of the base layer.
 3. The dressing of claim 1, wherein the central portion of the base layer is adapted to cover the tissue site and the periphery of the base layer is adapted to be positioned proximate to tissue surrounding the tissue site.
 4. The dressing of claim 1, wherein the apertures in the base layer are adapted to be in fluid communication with the tissue site and tissue surrounding the tissue site.
 5. The dressing of claim 1, wherein the base layer is comprised of silicone.
 6. The dressing of claim 1, wherein the adhesive is an acrylic adhesive.
 7. The dressing of claim 1, the base layer further comprising a border substantially surrounding the central portion and positioned between the central portion and the periphery, the border being substantially free of the apertures.
 8. The dressing of claim 7, wherein the apertures in the central portion of the base layer are positioned at the border and away from the border, and wherein the apertures positioned at the border are separated from one another by a greater distance than the apertures positioned away from the border.
 9. The dressing of claim 7, the border having a width between about 4 millimeters to about 11 millimeters.
 10. The dressing of claim 1, wherein the apertures in the periphery of the base layer have a diameter between about 9.8 millimeters to about 10.2 millimeters, and wherein the apertures in the central portion of the base layer have a diameter between about 1.8 millimeters to about 2.2 millimeters.
 11. The dressing of claim 1, at least three of the apertures in the corner of the periphery of the base layer being positioned in a triangular configuration and being smaller than other apertures in the periphery of the base layer.
 12. The dressing of claim 1, a plurality of the apertures in the periphery of the base layer being positioned at an edge and being fluid communication in a lateral direction with the edge, the apertures positioned at the edge being spaced substantially equidistant around the periphery of the base layer, the adhesive in fluid communication with the edge.
 13. The dressing of claim 1, at least one of the apertures in the periphery of the base layer being positioned in the corner of the periphery and being substantially precluded from fluid communication in a lateral direction exterior to the corner, the adhesive being substantially precluded from fluid communication exterior to the corner.
 14. The dressing of claim 1, wherein a plurality of the apertures in the periphery are positioned along an edge of the periphery and have an interior exposed at the edge.
 15. A method of manufacturing a dressing, comprising: providing a base layer, the base layer having a periphery surrounding a central portion; forming a plurality of apertures in the base layer; providing an adhesive configured to be in fluid communication with the plurality of apertures at least in the periphery of the base layer; providing a sealing member configured to be positioned adjacent the base layer, the sealing member having a periphery and a central portion; coupling at least a portion of the periphery of the base layer to the periphery of the sealing member to form an enclosure; disposing a first wicking layer in the enclosure; disposing a second wicking layer in the enclosure; and disposing an absorbent layer between the first wicking layer and the second wicking layer.
 16. The method of claim 15, further comprising providing a tissue interface configured to be positioned proximate a tissue site.
 17. The method of claim 16, further comprising covering the tissue interface and tissue surrounding the tissue site with the base layer.
 18. The method of claim 15, further comprising coupling a conduit interface to the sealing member and fluidly coupling the conduit interface to the enclosure.
 19. The method of claim 18, further comprising disposing an odor filter in the conduit interface.
 20. The method of claim 18, further comprising disposing a primary hydrophobic filter in the conduit interface.
 21. The method of claim 15, wherein forming a plurality of apertures in the base layer comprises cutting the base layer to form the plurality of apertures.
 22. The method of claim 15, wherein forming a plurality of apertures in the base layer comprises applying local RF energy to the base layer to form each of the plurality of apertures.
 23. The method of claim 15, wherein the plurality of apertures formed in the periphery of the base layer are larger than the apertures formed in the central portion of the base layer.
 24. The method of claim 15, wherein providing an adhesive comprises disposing the adhesive on a surface of the sealing member adapted to face the base layer.
 25. The method of claim 15, wherein the absorbent layer comprises a plurality of absorbent layers, and wherein the plurality of absorbent layers are positioned in fluid communication between the first wicking layer and the second wicking layer.
 26. The method of claim 25, further comprising disposing at least one intermediate wicking layer in fluid communication between the plurality of absorbent layers.
 27. The method of claim 15, further comprising disposing an anti-microbial layer in the enclosure.
 28. A method of treating a tissue site, comprising: disposing a tissue interface proximate the tissue site; positioning a dressing proximate the tissue interface, the dressing comprising: a base layer having a periphery surrounding a central portion and a plurality of apertures disposed through the periphery and the central portion, the apertures in the periphery being larger than the apertures in the central portion, wherein the base layer is adapted to cover the tissue interface and tissue surrounding the tissue site, an adhesive in fluid communication with the apertures at least in the periphery of the base layer, a sealing member having a periphery and a central portion, the periphery of the sealing member positioned proximate to the periphery of the base layer, wherein the central portion of the sealing member and the central portion of the base layer define an enclosure, a first wicking layer disposed in the enclosure, a second wicking layer disposed in the enclosure, an absorbent layer disposed between the first wicking layer and the second wicking layer, and a conduit interface positioned proximate to the sealing member and in fluid communication with the enclosure; applying a force to the sealing member, the force causing at least a portion of the adhesive to extend through the plurality of apertures; fluidly coupling a reduced-pressure source to the conduit interface; applying negative pressure from the reduced-pressure source to the tissue site; and drawing fluid through the plurality of apertures to the absorbent layer.
 29. The method of claim 28, wherein drawing fluid through the plurality of apertures to the absorbent layer further comprises wicking fluid along a surface of the first wicking layer and wicking fluid along a surface of the second wicking layer prior to absorption of the fluid by the absorbent layer.
 30. The method of claim 28, wherein the apertures in the base layer are adapted to be in fluid communication with the tissue site and tissue surrounding the tissue site.
 31. The method of claim 28, wherein the adhesive is adapted to be in fluid communication with tissue surrounding the tissue site through the apertures in the base layer.
 32. The method of claim 28, wherein the sealing member is adapted to provide a sealed space between the sealing member and the tissue site.
 33. The method of claim 28, wherein the adhesive is disposed on a surface of the sealing member adapted to face the base layer. 